This invention relates generally to analog timepiece movements, especially for wristwatches, intended to use thin large diameter energy cells. More particularly, the invention relates to an improved analog timepiece movement with a stepping motor designed to use a long life lithium energy cell.
Prior art quartz analog timepieces are designed to accommodate a button energy cell of relatively small diameter inside the movement, the diameter of the cell being less than half the diameter of the movement. An example of such a movement is seen in Reissue Patent Number 29,403, reissued Sep. 20, 1977 to Yamazaki. Since the life of the energy cell is related to its physical size, a longer life button cell must either be made in a larger diameter, or it must be made thicker. Thick wristwatches are undesirable. Various ingenious arrangements have been suggested in order to accommodate larger energy cells without increasing the size of the watch movement. In one such case, as illustrated in my U.S. Pat. No. 4,744,066 issued May 10, 1988 and assigned to the present assignee, a relatively large diameter energy cell was accommodated by arranging an intermediate wheel assembly so that its axis extended through the circumferential air gap between the stepping motor rotor and the stator.
Another arrangement is shown in U.S. Pat. No. 4,077,199 issued to Sakuma, et al on Mar. 7, 1978, in which the battery diameter extends beyond the center line of the timepiece, i.e., beyond the axis of rotation of the timepiece hands. Other efforts to increase the battery size include proposals of unusual energy cell configurations in shapes other than circular, as exemplified in U.S. Pat. No. 3,966,498 issued Jun. 9, 1976 to P. Wuthrich and assigned to the present assignee.
While suggestions have been offered in the prior art for "layering" or stacking up a large diameter energy cell with an integrated circuit, frame and electro-optic display in a sandwich construction, these layer constructions have been proposed for timepieces having no moving parts. It would be desirable to enjoy the advantages offered by thin large diameter lithium energy cells available today in a long life quartz analog watch.
In quartz analog watches, it may also be desirable to provide movements for new sizes of energy cells. This may involve redesign of the movement using a new arrangement of the stepping motor, gears, setting mechanism, and other internal parts. It would be desirable to increase the size of the energy cell for a particular movement without redesign of the movement.
Accordingly one object of the present invention is to provide an improved analog timepiece movement adapted to be operated by a large diameter energy cell.
Another object of the invention is to provide an improved quartz analog timepiece movement adapted to operate with a large diameter thin lithium energy cell.
Still another object of the invention is to provide an improved quartz analog timepiece movement adapted for various capacity energy cells without substantial redesign of the movement.